Activation of Vitamin D Regulates Response of Human Bronchial Epithelial Cells to Aspergillus fumigatus in an Autocrine Fashion

Figure 1

A. fumigatus induces the expression of 1α-hydroxylase and VDR and the conversion of 25D₃ to 1,25D₃ in 16HBE cells. (a) 16HBE cells were stimulated with resting conidia (RC) or swollen conidia (SC) [multiplicity of infection (MOI) = 1-2] for 2, 4, 8, 16, and 24 h. Nontreated 16HBE cells (basal) were used as controls. After treatment, cells were harvested and the protein and mRNA expression of 1α-hydroxylase and VDR was evaluated by Western blot analysis and quantitative real-time PCR, respectively. The Western blots illustrated are from one representative experiment of three separate ones, which are converted to densitometry units in graphs shown. 1α-Hydroxylase and VDR protein and mRNA expression was significantly upregulated in a time-dependent manner and peaked at 24 h after treatment with SC, whereas cells stimulated with RC showed no upregulation of 1α-hydroxylase and VDR protein and mRNA expression. All experiments were performed in triplicate on three consecutive days. Data shown are mean ± SE. Student’s -test, ^∗, ^∗∗, and ^∗∗∗, for comparison with baseline. (b) 16HBE cells were stimulated with RC or SC (MOI = 1-2) for 24 h in the presence of increasing doses of inactive vitamin D (25D₃), and active vitamin D (1,25D₃) was measured by ELISA in supernatants 24 h later. 16HBE cells converted the inactive vitamin D to the active form without other stimuli. 16HBE cells stimulated with SC generated greater amounts of active vitamin D in the presence of inactive vitamin D than cells without any treatment. RC stimulation did not influence the synthesis of active vitamin D in 16HBE cells. The graph reflects mean 1,25D₃ levels and SEM of three independent experiments. Student’s -test, ^∗ and ^∗∗, for comparison of SC challenged cells with cells without any treatment.

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